It is well known in the literature that Polyunsaturated Fatty Acids (PUFAs) of all types are highly susceptible to peroxide, free radical and light induced degradation including rancification and polymerization making them unsuitable for human consumption. For example, it is well known that flax seed oil, also known as linseed oil, readily undergoes free radical oxidation to advantageously form polymeric surfaces including oil based paints, hard furniture finishes and linoleum flooring. In addition, many companies offer flax seed oil for human consumption as a dietary supplement or food ingredient because of the high levels of PUFAs found in raw flax seed and its expeller pressed oils and more particularly Alpha-Linolenic Acid (ALA) and Linolenic Acid (LA). Many flax seed oil product labels suggest that the product must be refrigerated at all times due to the instability of such PUFAs in flax seed oil. Careful examination of the majority of commercially available flax seed oils obtained by expeller pressing, including those typically stored under refrigerated conditions, unfortunately reveals that they are unfit for human use based on their measured Peroxide Values (PVs). Such PV values above 3 meq/Kg (milliequivalents/gram) are deemed not suitable for salad oil applications and PV values above 10 meq/Kg are deemed to be unsuitable for human use because the measured PV value may be an early indicator of rancidity and free radical induced degradation. On the other hand, PV values taken alone do not adequately characterize such oils since a low PV value can also be associated with PUFA's that have already gone through the rancification process. Typical testing has revealed flax seed oil products sold for human consumption with observed PV's as high as 130 meq/kg also characterized with the odor associated with short chain aldehydes that make such oils “rancid” to olefactory senses.
Most raw seed based oils in common cooking and baking use, such as soybean, corn and canola seed oils naturally contain enough PUFAs making them unsuitable, without further processing, for use as cooking oils. Therefore unless such PUFA containing raw seed oils are hydrogenated to fully saturated triglycerides using hydrogen and a catalyst prior to their use in cooking applications, they are considered to be unfit for use as cooking oils. These oils are typically first isolated by, for example, expeller pressing the appropriate seed. The crude seed oil is then filtered to remove biomass. The resulting oil, containing significant levels of PUFAs, is then catalytically hydrogenated to reduce the PUFA content to levels suitable for use of the resulting oil in cooking applications. If the hydrogenation process is incomplete, however, the resulting mixtures are found to contain both undesirable heat labile PUFAs that quickly undergo rancification to small chain aldehydes in the resulting heated cooking oil as well as unsaturated trans-fatty acids which are believed to be detrimental to animal and especially human health.
Therefore, those skilled in the art will recognize the great difficulty in producing a shelf stable PUFA mixture wherein the PUFA content is as high as 70% wt/wt of the resulting seed extract from a natural seed source that then exhibits extraordinary room temperature stability.
Commonly assigned and copending patent application Ser. No. 13/231,131, filed Sep. 13, 2011, discloses a perilla seed oil extract that provides a healthy source of omega-3 and contains a very favourable ratio of ALA to LA (omega-3 to omega-6) of about 6:1 in one example. This perilla seed oil extract is obtained by pressing the perilla seeds to initiate seed cracking, processing the cracked biomass using supercritical CO2 fluid extraction, and collecting the extract to deliver more of the higher molecular weight compounds.
Commonly assigned and copending patent application Ser. No. 13/553,025 filed Jul. 19, 2012, and Ser. No. 13/937,537 filed Jul. 9, 2013, the disclosures which are hereby incorporated by reference in their entirety, disclose compositions and methods that enhance eye health, treat eye disorders, retard and ameliorate eye diseases and injuries, enhance other medical conditions such as cardiovascular health. The compositions include a mixture of carotenoids, including astaxanthin with phospholipid and triglyceride bound EPA and DHA derived from krill oil, in which the krill oil contains at least 30% total phospholipids and in a therapeutically effective amount to prevent, retard or treat eye and central nervous system diseases or injuries, such as age-related macular degeneration, cataract, dry eye syndrome due to glandular inflammation and other central nervous system degenerative diseases, photic injury, ischemic diseases, and inflammatory diseases, including related to the cardiovascular system. Krill oil is the oil based composition as used but other oils can be used. It is desirable, however, to use a perilla seed oil extract for eye health and related cardiovascular applications and take advantage of the benefits of various carotenoids.